Boats and Streams

The current of a stream at 1 kmph. A motor boat goes 35 km upstream and back to the starting point in 12 hours. The speed of the motor boat in still water is_________?

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The current of a stream at 1 kmph. A motor boat goes 35 km upstream and back to the starting point in 12 hours. The speed of the motor boat in still water is_________?

A. 6 kmph
B. 7 kmph
C. 8.5 kmph
D. 8 kmph
Explanation:
S = 1
M = x
DS = x + 1
US = x – 1
35/(x + 1) + 35/(x – 1) = 12
x = 6

A man whose speed is 4.5 kmph in still water rows to a certain upstream point and back to the starting point in a river which flows at 1.5 kmph, find his average speed for the total journey?

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A man whose speed is 4.5 kmph in still water rows to a certain upstream point and back to the starting point in a river which flows at 1.5 kmph, find his average speed for the total journey?

A. 8 kmph
B. 4 kmph
C. 2 kmph
D. 10 kmph
Explanation:
M = 45
S = 1.5
DS = 6
US = 3
AS = (2 * 6 * 3) /9 = 4

The current of a stream runs at the rate of 4 kmph. A boat goes 6 km and back to the starting point in 2 hours, then find the speed of the boat in still water?

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The current of a stream runs at the rate of 4 kmph. A boat goes 6 km and back to the starting point in 2 hours, then find the speed of the boat in still water?

A. 10 kmph
B. 21 kmph
C. 8 kmph
D. 12 kmph
Explanation:
S = 4
M = x
DS = x + 4
US = x – 4
6/(x + 4) + 6/(x – 4) = 2
x = 8

A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and black. What is the total distance traveled by the man?

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A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and black. What is the total distance traveled by the man?

A. 6.24 km
B. 6 km
C. 5.76 km
D. 5.66 km
Explanation:
M = 6
S = 1.2
DS = 7.2
US = 4.8
x/7.2 + x/4.8 = 1
x = 2.88
D = 2.88 * 2 = 5.76

A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and black. How far is the place?

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A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and black. How far is the place?

A. 3.12 km
B. 2.88 km
C. 3 km
D. 2 km
Explanation:
M = 6
S = 1.2
DS = 6 + 1.2 = 7.2
US = 6 – 1.2 = 4.8
x/7.2 + x/4.8 = 1
x = 2.88